The invention relates to a method of applying a lining material to a conduit and in particular but not exclusively to a method of applying a lining material to a pipe or a chimney flue. The invention also relates to an apparatus for applying a lining material to a conduit.
Conduits such as sewer or water pipes are generally relined with cement using a spraying system. One problem with such known methods, however, is that it is difficult to maintain a regular thickness of sprayed material. This is particularly the case with sewer or water pipes which are less then one meter in diameter.
The use of solid fuel appliances has accelerated the deterioration of chimney flues in domestic dwellings. In many cases domestic chimney flues built over the last century and made redundant during the period of cheap oil are now being brought back into use and it is generally necessary to re-line the flues of these chimneys in order to meet appropriate standards.
One known method of relining the flues of such chimneys is to thread a flexible stainless steel or galvanised pipe through the existing flue. This is a difficult and time consuming operation particularly when trying to accommodate bends in the chimney. In addition, stainless or galvanised steel are no longer acceptable materials as they do not meet the standards required for solid fuel chimneys.
It is also known to re-line a flue with a non-combustible light-weight cement by first inserting a flexible inflatable core into the flue, usually from the top, and then pumping or pouring wet mixed lining material around the core. This method normally requires acess to the top of the chimney and it may take at least twenty-four hours for the lining material to set before the core can be removed. Thus, two visits to the chimney site are normally required, one for carrying out the lining operation and the other to remove the core. In addition, because of its light-weight character the lining material in this case must be applied in a thick layer which presents difficulties of adhesion and the lining material generally occupies an excessive proportion of the designed cross sectional area which reduces the efficiency of the flue.
In both the prior art relining methods described it is difficult to maintain a rectangular cross-section which is used in many chimneys.